LN CSAC GPSDO Low Noise Chip Scale Atomic Clock GPS Disciplined Oscillator

GPS disciplined chip scale atomic clock with an ultra-low noise SC-cut ovenized crystal post-filter and built-in distribution amplifier.

Long-Term Oscillator Aging: Less than 0.3 ppb per month in holdover without GPS; Zero aging with GPS
Frequency Stability Over Temperature: Better than ±0.5E-09
1 PPS Accuracy: ±15 ns to UTC RMS (1-Sigma)
Holdover Stability after 96 hours warmup: <±2 µs over 24 Hour Period

Datasheet

Overview

The LN CSAC GPSDO combines a Cesium Vapor Cell reference oscillator with a high-precision, ovenized, SC-cut crystal oscillator. The pairing is designed for fast warm-up, holdover, low power consumption, and phase noise and Allan Deviation (ADEV) performance in the xE-012 range.

By combining the strengths of both oscillators, the module is positioned as an alternative to commercially available Cesium reference clocks at a lower cost than legacy products. It provides GPS disciplining, holdover capability, low power consumption and a small size.

The LN CSAC GPSDO is form, fit and function compatible with the CSAC GPSDO boards, so customers upgrading from the standard CSAC GPSDO platform do not need to make design-in changes.

Key Features

Ultra low noise SC-cut post-filter
1E-012 ADEV stability at 1 s
Built-in distribution amplifier
Form, fit, and function compatible with CSAC GPSDO boards
Four isolated 10 MHz sine wave outputs and one 5 MHz CMOS output
50-channel GPS receiver with SBAS (WAAS, EGNOS, MSAS) support
SCPI-99 control over RS-232/USB

Specifications

Frequency and Timing

Long-Term Oscillator Aging	Less than 0.3 ppb per month in holdover without GPS; Zero aging with GPS
Frequency Stability Over Temperature	Better than ±0.5E-09 CSAC only, no GPS Disciplining, 0°C to +75°C
1 PPS Accuracy	±15 ns to UTC RMS (1-Sigma) GPS Locked in Position Hold mode
Holdover Stability after 96 hours warmup	<±2 µs over 24 Hour Period @+25°C (after 20 minutes with GPS lock)
Warm Up Time/Stabilization Time Without GPS	CSAC: <3 min, Filter: <12 min +25°C to <5E-010 Accuracy Typical

ADEV (DOCXO after 24 hours with GPS lock)

1 s	<2E-12 Web page highlights state 1E-012 ADEV stability at 1 s; datasheet table value shown
10 s	<6E-12
100 s	<7E-12
1K s	<7E-12
10K s	<2E-12

Phase Noise (standard temp DOCXO option)

1 Hz offset	CSAC: NA; Filter: -100 dBc/Hz Web page highlights state 110 dBC/Hz at 1 Hz; datasheet table value shown
10 Hz offset	CSAC: -90 dBc/Hz; Filter: -135 dBc/Hz
100 Hz offset	CSAC: -125 dBc/Hz; Filter: -145 dBc/Hz
1 kHz offset	CSAC: -145 dBc/Hz; Filter: -150 dBc/Hz
10 kHz offset	CSAC: -152 dBc/Hz; Filter: -155 dBc/Hz
100 kHz offset	CSAC: -153 dBc/Hz; Filter: -155 dBc/Hz

Outputs

1 PPS Output (CSAC Flywheel Generated)	5 V CMOS output, can be shifted in 1 ns steps relative to UTC
10 MHz Output, 5 MHz Output	Four Isolated 10 MHz Sine Wave +13 dBm ±3 dBm, one 5 MHz CMOS 5 V
Distribution Amplifier Port Isolation, 2 MHz	>98 dB
Distribution Amplifier Port Isolation, 10 MHz	>85 dB
TTL Alarm Output	GPS Unlock and Hardware Failure indicator

Control and Interfaces

RS-232/USB Control	SCPI-99 Control at 9.6 K, 19.2 K, 38.4 K, 57.6 K, 115.2 K
RS-232 and TTL NMEA Output Sentences	NMEA 0183 rev. 2.3, Sentences: GGA, RMC, ZDA, PASHR, and others
USB, LCD Support	RS-232 or USB controlled, supports 16x2 LCD Displays

GPS Receiver

GPS Frequency, Antenna	L1 C/A 1574 MHz, Passive or Active Antenna 5 V, MMCX Connector
GPS Receiver	50 Channels, Mobile, SBAS: WAAS, EGNOS, MSAS supported
Sensitivity, Acquisition	-144 dBm
Sensitivity, Tracking	-160 dBm
GPS Receiver Motion Adaptive Filter Settings	Optimized depending on vehicle velocity (Auto-sensing, Auto-switching)

Power

Supply Voltage (Vdd)	12 V, ±1 V
Power Consumption	<5 W at +25°C steady-state, <9 W warmup

Environmental

Operating Temperature	-10°C to +70°C
Storage Temperature	-45°C to +85°C
g-sensitivity	CSAC: <0.2 ppb/g/axis, Filter: <0.3 ppb/g/axis Filter value with low-g option
Magnetic Sensitivity	Less than 0.4 ppb per Gauss long term
MTBF	>100,000 Hours 0°C to +70°C

Specifications are taken from the manufacturer's documentation. See the datasheet for complete and current values.

Applications

Radar transmitters and radar front-ends
Astronomy applications
Test equipment references
Ultra low phase noise Ka, Ku, C band up and down-conversion for satellite communications
Manufacturing testing of crystal oscillators (TCXO, OCXO, Cesium, Rubidium)
High entropy radio communications
House/lab time and frequency standards
Military high-grade jammers and spoofers
Defense
5G communications
SATCOM
Transportation
Data center
Energy
Financial
Critical infrastructure